The present invention relates to an apparatus for determining the existence of a foreign body, such as a piece of metal or the like, in a textile fiber bale, the apparatus including a search device for detecting the foreign body.
The presence of a foreign body, such as a piece of iron banding, wire, a tool, etc., in a textile fiber bale may cause damage to the initial processing machine, for example, the bale opener, possibly starting a fire in that or a subsequent processing machine. Further, a foreign body in a fiber bale may undesirably get into further sections of the fiber processing system.
In a known device, mechanical sensor elements detect only electrically conductive foreign bodies. In order to be detected, however, these foreign bodies must be free of fiber tufts and must be disposed at the surface of the bale. The drawback of this device is that such exposed foreign bodies are not detected in time to prevent them from being removed, together with the uppermost layer of fiber tufts, by the initial processing machine and sucked into that machine. Further, it is generally already too late to avoid the removal and extraction of the foreign bodies, since a processing machine, such as a bale opener, cannot be shut off quickly enough to prevent such foreign bodies from entering the machine. Another annoying factor is that only foreign bodies having a size of a certain order of magnitude can be detected by the known detecting device. Smaller pieces such as bottle caps cannot be clearly identified.